INTRODUCTION 



TO 



B O T A N 



B O O K I. 



organography; or, of the structure of plants. 



CHAPTER I. 



OF THE ELEMENTARY ORGANS. 



If plants are considered with reference to their internal 

 organization, they appear at first sight to consist of a vast 

 multitude of exceedingly miiuite cavities, separated by a 

 membranous substance ; more exactly examined, it is found 

 that these cavities have a variety of different figures, and 

 that each is closed up from those that surround it ; if the 

 inquuy is carried still farther, it will be discovered that the 

 partitions between the cavities are all double, and that by 

 maceration in water, or by other methods, the cavities with 

 their enclosing membrane may be separated from each other 

 into distinct bodies. These bodies constitute what is called 

 Vegetable Tissue, or Elementary Organs : they are the Simi- 

 lary parts of Grew ; the Tissu organique of Mirbel ; and the 

 Parties elementaires, or Parties similaires, of De Candolle. 



Tlie chemical basis of the elementary organs has been 

 found to be oxygen, hydrogen, and carbon, with occasionally 

 a little nitrogen or azote, combined in various proportions : 

 their organic basis is membrane and fibre. The latter only 

 are here to be considered. 



